Tech: 1,200hp Shelby GT500 Build

Four-Digit Fun

Boost Works creates a super Shelby for the street—and the Texas Mile

By Steve Turner
Photos courtesy of Boost Works

It’s a safe bet that most people reading this site dream of a Mustang with huge horsepower. Some of us want a street car that pushes the limits of that moniker. Others want an all-out race car that pushes the envelope of the record book. Sometimes, those two wishes intersect in one car.

Those wheels are True Forged Competition three-piece wheels, 20×9 in front and 20×11 in the rear. For the street, they roll on Nitto 275/35-20 and 305/35 555R, respectively. When it runs at the Texas Mile, Boost Works swaps the street tires in favor of a set of Pirelli DH road racing slicks. Its suspension is sharpened with Eibach springs, BMR sway bars, and a BMR Panhard bar.

In the case of this 2012 Shelby GT500, it was built to behave on the street and cut loose on The Texas Mile with just north of 1,200 rear-wheel horsepower.

“We’ve sponsored and attended the Texas Mile for a few years, now. Usually, we go to watch, and give Mark and Kevin over at M2K Motorsports a hand in the pits with their 278-mph Ford GT. That’s always fun, but we decided last year to put a car together to go and get our feet wet,” Travis Burelle of Boost Works explained. “One of our customers brought us a 2012 GT500, and wanted to build something that he could use as a high-powered street car, and for mile racing.”

A Boost Works customer brought this 2012 Shelby GT500 in for a high-powered, mile-racing transformation. He left with a 6.0-plus-liter stroker engine topped by a 4.2-liter Kenne Bell Mammoth, which put down over 1,200 horsepower to the wheels. Despite its four-digit street cred, the interior of this powerhouse Shelby’s interior is nearly factory stock save for the shifter. That shifter is attached to a prepped Tremec TR-6060 six-speed manual fitted with a McLeod RXT twin-disc clutch. This car is definitely a sleeper.

Apparently, getting their feet wet meant pushing all the chips in and betting on the winning combination of big cubes and big boost.

“Having built every variation of modular Ford engines now for almost 15 years, we approached this project with the idea of building the largest-displacement modular Ford engine that we could safely produce,” he explained. “We didn’t want to have excessive piston speeds or pumping losses, and we wanted to let our ported GT heads work their magic.”

With those heads, the big-bore 5.4 and Kenne Bell Mammoth definitely made magic. Even during its early testing phases—with lower boost and conservative timing—it broke into the four-digit range…

Building the engine was one thing. They also upgraded the rest of the car to support this kind of power. However, they didn’t go full-race-car from the jump. Aside from a sweet set of True Forged wheels, the car looks pretty stock. I didn’t even have a roll cage, which would limit just how fast it could legally run at a mile race.

How fast do you want to go? Kenne Bell offers Mustang superchargers from 2.1 liters to 4.2 liters. For the GT500, the common Kenne Bell blower displacements are 2.8 and 3.6 liters. For most combos, these offer plenty of power, up to 750 and 1,000 horsepower, respectively. Here is a comparison of the 3.6-liter (left) and the 4.2-liter Mammoth units. The 4.2 is good for 1,300 horsepower.

“On our first trip out to the Texas Mile last fall, we ran the car at 1,000whp on C85, with a very conservative timing map. After fighting traction all weekend, we finally laid down a respectable 164mph half-mile speed. The car didn’t have a cage yet, and we were not allowed to go over 199 mph,” Travis said. “We also had a slightly small diameter tire for the rear gear we were running. We topped out Fifth gear at around the 3/4-mile mark, with the data-log showing 201 mph at that point. Not wanting any part of Sixth gear at full power (and not wanting to piss off the track officials), we coasted through the 1-mile mark at roughly our half-mile speed.”

As you can see below, the Boost Works GT500 certainly proved up to the task of running at top speed, and so far, this super Shelby has proven itself in every arena.

“This is a full-weight car, with stock aero, and it will do in excess of 200 mph in the standing mile with no problems,” he added. “Our engine has held up well throughout testing, including 50-plus dyno pulls, six passes down the track, and over 500 miles of street testing.”

Now, the next step is to fit it with a cage and wider tire and let it eat. For now, just enjoy it pulling hard on the street…

Though the shop originally planned on a stock-displacement build, Boost Works eventually stepped up to an offset-ground Cobra Jet crankshaft that was nitrided to restore the journal hardness.Beginning with a fresh, iron 5.4-liter block from Ford, Boost Works commissioned Modular Motorsports Racing to install a set of 3.7-inch Darton sleeves. MMR also half-filled the water jackets, and the upper portion was left to circulate coolant. “This gave us a good ratio of structural support, sealing, and cooling,” Travis Burelle of Boost Works explained.The aforementioned CJ crank spins Manley 300m billet rods secured with ARP 2000 fasteners. They swing Manley 2618 forged pistons fitted with stainless rings.Upon receiving the fortified block back from MMR, the crew at Boost Works assembled the short-block with ARP fasteners.Knowing the intended performance level of this engine, Boost Works stepped up from the factory head bolts to ARP head studs. Likewise, the head gaskets were upgraded with Cometic multi-layer-steel gaskets designed for the big-bore block.The heads secured by those studs are none other than Ford GT cylinder heads treated to CNC porting. They are fitted with valves 1mm larger in diameter. Those valves are controlled by PAC alloy springs.Comp Cams ground a set of custom blower cams to Boost Works specs for this engine combination. Understandably, the crew at Boost Works wasn’t keen to give up the specs on these sticks, but based on the engine’s performance, they clearly work.An Achilles’ Heel of high-powered modular engines can be the stock oil pump drive gears. To ensure the engine was fortified at every level, Boost Works upgraded the oil pump with a set of MMR Hurricane billet oil pump gears that are built to withstand up to 2,000 horsepower.How about 10.2 liters of Ford Performance? Yes, that’s a 4.2-liter Kenne Bell Mammoth atop a robust, nearly 6.1-liter modular engine.On everyday pump E85, this Shelby puts down 925 rear-wheel horsepower on 20 pounds of boost. However, running VP’s racy C85 it ramped up to 1,030 horsepower at the feet. What you see here is the result of 28 pounds of boost and VP C26 race fuel. Yup, that is 1, 241 horsepower and 1,047 lb-ft of torque!Installed in the car, the 4.2-liter blower’s Mammoth inlet is fed by a 168mm monoblade throttle body and a 4 ½-inch inlet tube. Fueling this combo is Boost Works’ 1,500-horsepower fuel system, which is based on three Walbro 465 fuel pumps in a Fore Innovations fuel hat. Plumbed into the -8 feed line and -6 return line is a Fore regulator, which mandates the proper pressure for the Fuel Injector Clinic injectors.In some shakedown testing, the car ran as fast as 164 mph at the half-mile mark, but since it didn’t have a cage, they couldn’t run it out the back door. Before it heads to the Texas Mile, it will have a roll cage and wider rear tires. With those upgrades, the Boost Works crew hopes to run in the 210- to 215-mph range. It puts down all that power through a Auburn Pro differential and 35-spline Moser axles.